Maximum items
Pause game play. Then, hold C + Z and quickly press Down, Up, Down, Up, Right, Left, Right, Left two times, 1, 2. You will get a set of three items. Repeat the code to get the next set of items, in the order they would normally appear during game play. You can repeat the code until getting the desired item, and it will eventually cycle back to the first three items. Note: The Ninja Tabi, Colored Rice, and Devil's Mask will not work correctly if obtained through this code.

All missions and assignments
Hold C + Z and quickly press Left four times, Right four times, 1, 2 at the title screen.

Shadow mode
Swing the Wiimote at the level selection screen. The screen will change colors and the Shadow mode level selection screen will appear. Shadow mode is more difficult with additional enemies and routes.

Unlockables

Ancient Hissatsu techniques
Complete 30 assignments.

Colored Rice
Complete 50 assignments.

Concept art gallery
Complete 10 assignments.

Memories video gallery
Complete 40 assignments.

Sound and music
Complete 20 assignments.

Devil's Mask
Get all twenty mask pieces in Shadow mode.

Speed Socks
Successfully complete the game under the Normal difficulty setting. Note: You cannot earn an "A" or "S" rank when they are equipped.

Get all of the map pieces in stages 1 through 5, and stage 10 to unlock Izayoi, Rikimaru's unbreakable sword.
Ninja Tabi '08

Successfully complete Story mode.
Get all of the map pieces in stages 6 through 9 to unlock Onibi, Ayame's unbreakable sword.

Map piece locations

Map pieces can be found at the following locations in Normal mode.

Mission 1

Stage 2 (alternate): Scale the wall with Kasugai in the start of Stage 1 to get to the alternate Stage 2 path. There is a map piece next to the locked door inside the building.
Stage 5: Follow the girl until finding a candle in front of a doorway. Go outside and turn left. The map piece is in the corner on the ground.

Mission 2

Stage 1 (alternate): Destroy the wall with a Ghostmaker to the left after crossing the bridge. Enter the hut on the left after crossing through the doorway. The map piece is next to the ninja.
Stage 3: Climb onto the rafters of the house and drop into the room with the closed doors. The map is on the floor.

Mission 3

Stage 1: When climbing out of the trench, turn to the right and move the boxes out of the way. Go through the crawlspace.
Stage 3: Up the staircase in the center of the three enemies that are taken out with a smoke grenade.

Mission 4

Stage 2: Near the wagon.
Stage 3: On the bridge.

Mission 5

Stage 1: On the edge of the cliff in a bush against the wall that leads to the next mission.
Stage 2: Jump across the broken bridge near the end of the mission. The map is on the ground.

Mission 6

Stage 2: Use the Shinobi Cat to get behind the boxes in the corner next to the doors near the end of the area.
Stage 3: Near the end of the area, there is a hole in the building. Send the Shinobi Cat into it and collect the map piece.

Mission 7

Stage 1: Use the Shinobi Cat to enter the left-most hut and get the piece of the map.
Stage 4: Use the Shinobi Cat to enter the small hole in the crawlspace behind the armored samurai against the back wall.

Mission 8

Stage 2: In the smallest room of the house.
Stage 7: The piece is on the floor of the large room inside the house.

Mission 9

Stage 1: Use the Kasugai to scale the wall near the beginning of the mission. Walk to the end of the cliff and collect the map piece.
Stage 2: Follow the path all the way to the end. Instead of turning towards the end of the level, continue straight. The map piece is on the floor in front of the closed doors

Mission 10

Stage 2: When appearing in the level at the main doors, move towards the right-most wall. Note: This is where you will appear if you scaled the wall with Kasugai. Proceed forward into the room. The map is on the floor in the corner.
Stage 4: Climb onto the rafters to the right of the starting point. Continue all the way along the rafters and drop down to find the final map piece.

Map pieces can be found at the following locations in Shadow mode.

Mission 1

Stage 2 (alternate): Scale the wall with Kasugai to get to the next area. Inside the house, go down the corridor next to the locked door to find the map piece.
Stage 3 (alternate): On the floor in the corridor just past the small room.

Mission 2

Stage 2: In the middle of the floor inside the house.
Stage 3: When moving towards the lake, turn to the right and go to the small table near the wall. Use a Fishing Rod to hook the map from the awning of the house next to you.

Mission 3

Stage 1: Use a Ghostmaker to destroy the wall to the right after the fence in front of the starting position. Enter the building at the end of the corridor. The map piece is in the middle of the floor. Alternately, use the Shinobi Cat to go through the hole to the right of the second fence into the same building.
Stage 5: Climb the box and enter the hole into the room with Tado in it. Climb on the rafters towards the opening in the back of the room. Drop down and collect the map piece from the outside balcony.

Mission 4

Stage 2: When appearing in the level at the main doors, move towards the right-most wall. Note: This is where you will appear if you had scaled the wall with the Kasugai. Proceed forward into the room. The map is on the floor in the corner.
Stage 7: The map piece is near the back wall of the largest room.

Mission 5

Stage 3: Cross the bridge and edge between the two buildings. The map piece is on the ground in the bushes between two hidden ninja.
Stage 6: Use Poison or a Ninjato to destroy the gold lock on the building near the starting location. The map piece is inside the building.

Mission 6

Stage 3: Immediately after starting, kill the gunman on the bridge. A map piece will fall on the bridge where the gunman died. Use a Fishing Rod to retrieve it.
Stage 4: The map piece is at the end of the corridor-like area you start in. Note: It is easier to go to the left and into the house, get the Shinobi Cat, then have him get the piece.

Mission 7

Stage 3: In the center of the large room, near the pile of boxes.
Stage 4: In the furthest room of the house. You must climb onto the rafters to sneak past the merchant and then drop down and grab the map.

Mission 8

Stage 2 (alternate): Use the Kasugai to climb the wall behind the starting point. The map piece is on the floor in the room with a group of armored samurai and a ninja.
Final Stage: Use the Fishing Rod to get the map piece off the awning of the entrance to the weapon supplies shed (the white door).

Mission 9

Stage 1: Scale the wall with Kunai and run to the far end of the cliff. A map piece is on the edge.
Stage 4: Upstairs in the house with a cat standing inside of it.

Mission 10

Stage 7: After dropping off of the rafters, go to the far end of the corridor and use a Ghostmaker to destroy the wall. The map piece is on the floor.
Stage 7: After getting the last map piece, use the Shinobi Cat to walk through the room. Pass through the tables and walk by the armored samurai into the next room. From here, move towards the other two armored samurai and turn left. Pass through the hole in the wall and collect the map piece.